Cargo Features

c-map has no features set by default.

[dependencies]
c-map = { version = "0.2.1", features = ["parking-lot"] }
parking-lot = parking_lot

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

parking_lot parking-lot?